""" PickleRPC provides a Server object for connection to Pickle-RPC servers for the purpose of making requests and receiving the responses. >>> from MiscUtils.PickleRPC import Server >>> server = Server('http://localhost/cgi-bin/WebKit.cgi/Examples/PickleRPCExample') >>> server.multiply(10,20) 200 >>> server.add(10,20) 30 See also: Server, Webkit.PickleRPCServlet, WebKit.Examples.PickleRPCExample UNDER THE HOOD Requests look like this: { 'version': 1, # default 'action': 'call', # default 'methodName': 'NAME', 'args': (A, B, ...), # default = (,) 'keywords': {'A': A, 'B': B, ...} # default = {} } Only 'methodName' is required since that is the only key without a default value. Responses look like this: { 'timeReceived': N, 'timeReponded': M, 'value': V, 'exception': E, 'requestError': E, } TimeReceived is the time the initial request was received. TimeResponded is the time at which the response was finished, as close to transmission as possible. The times are expressed as number of seconds since the Epoch, e.g., time.time(). Value is whatever the method happened to return. Exception may be 'occurred' to indicate that an exception occurred, the specific exception, such as "KeyError: foo" or the entire traceback (as a string), at the discretion of the server. It will always be a non-empty string if it is present. RequestError is an exception such as "Missing method in request." (with no traceback) that indicates a problem with the actual request received by the Pickle-RPC server. Value, exception and requestError are all exclusive to each other. SECURITY Pickle RPC uses the SafeUnpickler class (in this module) to prevent unpickling of unauthorized classes. By default, it doesn't allow _any_ classes to be unpickled. You can override allowedGlobals() or findGlobal() in a subclass as needed to allow specific class instances to be unpickled. Note that both Transport in this module and PickleRPCServlet in WebKit are derived from SafeUnpickler. CREDIT The implementation of this module was taken directly from Python 2.2's xmlrpclib and then transformed from XML-orientation to Pickle-orientation. The zlib compression was adapted from code by Skip Montanaro that I found here: http://manatee.mojam.com/~skip/python/ """ __version__ = 1 # version of PickleRPC protocol import types try: from cPickle import dumps, Unpickler, UnpicklingError except ImportError: from pickle import dumps, Unpickler, UnpicklingError try: import zlib except ImportError: zlib = None try: from cStringIO import StringIO except ImportError: from StringIO import StringIO class Error(Exception): """ The abstract exception/error class for all PickleRPC errors. """ pass class ResponseError(Error): """ These are unhandled exceptions raised when the server was computing a response. These will indicate errors such as: * exception in the actual target method on the server * malformed responses * non "200 OK" status code responses """ pass # Sometimes xmlrpclib is installed as a package, sometimes not. So we'll # make sure it works either way. try: from xmlrpclib.xmlrpclib import ProtocolError as _PE except ImportError: from xmlrpclib import ProtocolError as _PE # @@ 2002-01-31 ce: should this be caught somewhere for special handling? Perhaps in XMLRPCServlet? class ProtocolError(ResponseError, _PE): pass class RequestError(Error): """ These are errors originally raised by the server complaining about malformed requests. """ pass class InvalidContentTypeError(ResponseError): def __init__(self, headers, content): Exception.__init__(self) #, headers, content) self.headers = headers self.content = content def __repr__(self): content = self.content return '%s: Content type is not text/x-python-pickled-dict\nheaders = %s\ncontent =\n%s' % ( self.__class__.__name__, self.headers, content) __str__ = __repr__ class SafeUnpickler: """ For security reasons, we don't want to allow just anyone to unpickle anything. That can cause arbitrary code to be executed. So this SafeUnpickler base class is used to control what can be unpickled. By default it doesn't let you unpickle any class instances at all, but you can create subclass that overrides allowedGlobals(). Note that the PickleRPCServlet class in WebKit is derived from this class and uses its load() and loads() methods to do all unpickling. """ def allowedGlobals(self): """ Must return a list of (moduleName, klassName) tuples for all classes that you want to allow to be unpickled. Example: return [('mx.DateTime', '_DT')] allows mx.DateTime instances to be unpickled. """ return [] def findGlobal(self, module, klass): if (module, klass) not in self.allowedGlobals(): raise UnpicklingError, 'For security reasons, you can\'t unpickle objects from module %s with type %s' % (module, klass) globals = {} exec 'from %s import %s as theClass' % (module, klass) in globals return globals['theClass'] def load(self, file): safeUnpickler = Unpickler(file) safeUnpickler.find_global = self.findGlobal return safeUnpickler.load() def loads(self, str): return self.load(StringIO(str)) # @@ 2002-01-31 ce: Could we reduce code duplication and automatically # inherit future improvements by actually importing and using the # xmlrpclib classes below either as base classes or mix-ins? class Server: """uri [,options] -> a logical connection to an XML-RPC server uri is the connection point on the server, given as scheme://host/target. The standard implementation always supports the "http" scheme. If SSL socket support is available (Python 2.0), it also supports "https". If the target part and the slash preceding it are both omitted, "/PickleRPC" is assumed. See the module doc string for more information. """ def __init__(self, uri, transport=None, verbose=0, binary=1, compressRequest=1, acceptCompressedResponse=1): # establish a "logical" server connection # get the url import urllib type, uri = urllib.splittype(uri) if type not in ("http", "https"): raise IOError, "unsupported Pickle-RPC protocol" self.__host, self.__handler = urllib.splithost(uri) if not self.__handler: self.__handler = "/PickleRPC" if transport is None: if type == "https": transport = SafeTransport() else: transport = Transport() self.__transport = transport self.__verbose = verbose self.__binary = binary self.__compressRequest = compressRequest self.__acceptCompressedResponse = acceptCompressedResponse def _request(self, methodName, args, keywords): """ Call a method on the remote server. """ request = { 'version': 1, 'action': 'call', 'methodName': methodName, 'args': args, 'keywords': keywords, } if self.__binary: request = dumps(request, 1) else: request = dumps(request) if zlib is not None and self.__compressRequest and len(request) > 1000: request = zlib.compress(request, 1) compressed = 1 else: compressed = 0 response = self.__transport.request( self.__host, self.__handler, request, verbose=self.__verbose, binary=self.__binary, compressed=compressed, acceptCompressedResponse=self.__acceptCompressedResponse ) return response def __requestValue(self, methodName, args, keywords): dict = self._request(methodName, args, keywords) if dict.has_key('value'): return dict['value'] elif dict.has_key('exception'): raise ResponseError, dict['exception'] elif dict.has_key('requestError'): raise RequestError, dict['requestError'] else: raise RequestError, 'Response does not have a value, expection or requestError.' def __repr__(self): return "<%s for %s%s>" % (self.__class__.__name__, self.__host, self.__handler) __str__ = __repr__ def __getattr__(self, name): # magic method dispatcher return _Method(self.__requestValue, name) ## note: to call a remote object with an non-standard name, use ## result getattr(server, "strange-python-name")(args) ServerProxy = Server # be like xmlrpclib for those who might guess or expect it class _Method: """ Some magic to bind a Pickle-RPC method to an RPC server. Supports "nested" methods (e.g. examples.getStateName). """ def __init__(self, send, name): self.__send = send self.__name = name def __getattr__(self, name): return _Method(self.__send, "%s.%s" % (self.__name, name)) def __call__(self, *args, **keywords): # note that keywords are supported return self.__send(self.__name, args, keywords) class Transport(SafeUnpickler): """ Handles an HTTP transaction to a Pickle-RPC server. """ # client identifier (may be overridden) user_agent = "PickleRPC/%s (by http://webware.sf.net/)" % __version__ def request(self, host, handler, request_body, verbose=0, binary=0, compressed=0, acceptCompressedResponse=0): # issue Pickle-RPC request h = self.make_connection(host) if verbose: h.set_debuglevel(1) self.send_request(h, handler, request_body) self.send_host(h, host) self.send_user_agent(h) self.send_content(h, request_body, binary, compressed, acceptCompressedResponse) errcode, errmsg, headers = h.getreply() if errcode != 200: raise ProtocolError( host + handler, errcode, errmsg, headers ) self.verbose = verbose if h.headers['content-type'] not in ['text/x-python-pickled-dict', 'application/x-python-binary-pickled-dict']: headers = h.headers.headers content = h.getfile().read() raise InvalidContentTypeError(headers, content) try: content_encoding = headers["content-encoding"] if content_encoding and content_encoding == "x-gzip": return self.parse_response_gzip(h.getfile()) elif content_encoding: raise ProtocolError(host + handler, 500, "Unknown encoding type: %s" % content_encoding, headers) else: return self.parse_response(h.getfile()) except KeyError: return self.parse_response(h.getfile()) def make_connection(self, host): # create a HTTP connection object from a host descriptor import httplib return httplib.HTTP(host) def send_request(self, connection, handler, request_body): connection.putrequest("POST", handler) def send_host(self, connection, host): connection.putheader("Host", host) def send_user_agent(self, connection): connection.putheader("User-Agent", self.user_agent) def send_content(self, connection, request_body, binary=0, compressed=0, acceptCompressedResponse=0): if binary: connection.putheader("Content-Type", "application/x-python-binary-pickled-dict") else: connection.putheader("Content-Type", "text/x-python-pickled-dict") connection.putheader("Content-Length", str(len(request_body))) if compressed: connection.putheader("Content-Encoding", "x-gzip") if zlib is not None and acceptCompressedResponse: connection.putheader("Accept-Encoding", "gzip") connection.endheaders() if request_body: connection.send(request_body) def parse_response(self, f): return self.load(f) def parse_response_gzip(self, f): # read response from input file, decompress it, and parse it # @@ gat: could this be made more memory-efficient? return self.loads(zlib.decompress(f.read())) class SafeTransport(Transport): """ Handles an HTTPS transaction to a Pickle-RPC server. """ def make_connection(self, host): # create a HTTPS connection object from a host descriptor # host may be a string, or a (host, x509-dict) tuple import httplib if isinstance(host, types.TupleType): host, x509 = host else: x509 = {} try: HTTPS = httplib.HTTPS except AttributeError: raise NotImplementedError,\ "your version of httplib doesn't support HTTPS" else: return apply(HTTPS, (host, None), x509) def send_host(self, connection, host): if isinstance(host, types.TupleType): host, x509 = host connection.putheader("Host", host)